FR2460897A1 - SLUDGE TREATMENT PROCESS - Google Patents

Abstract

PROCESS FOR THE TREATMENT OF SLUDGE CONTAINING ORGANIC MATERIALS, BY COAGULATION AND SOLID-LIQUID SEPARATION. A FIBER, AT A RANGE OF 0.05 TO 150 BY WEIGHT IN RELATION TO THE SOLID MATERIALS CONTAINED IN THE MUD, AND A NON-ORGANIC COAGULANT OR A POLYMER, ARE ADDED TO THE SLUDGE, IN ORDER TO COAGULATE THE SLUDGE. THE WATER IS REMOVED FROM COAGULATED SLAB, IN ORDER TO OBTAIN A LOW WATER FILTER CAKE. THE INVENTION APPLIES PARTICULARLY TO THE TREATMENT OF URBAN OR INDUSTRIAL WASTE WATER SLUDGE, WASTE MATERIALS, SUPPLY WATER TREATMENT SLUDGE, OR SLUDGE DEPOSITED AT THE BOTTOMS OF RIVERS, PORTS, LAKES AND SEAS.

Description

The present invention relates to a method of

  sludge treatment, such as residual water sludge

  buildings, drainage materials, water sludge

  tation, sludge deposited at the bottom of rivers, lakes, ports, and seas and sludge of industrial waste. More particularly, the present invention relates to a sludge treatment method suitable for solid coagulation and solid-liquid separation in sludges containing organic matter and fine particles.

of mineral matter.

  For the disposal of sludge, it is generally

  a process in which a coagulant is added to a

  mud to coagulate solids. The separation

  liquid-liquid is then carried out, or coagulative solids

  They are dehydrated mechanically to obtain a dehydrated sludge of reduced volume. The dewatered sludge is discharged as it is, or it is rejected in the form of

  ash after incineration, or it is solidified by

  corporation of a material of solidification.

  Sludge rich in organic matter, for example

  Urban sewage sludge contains large amounts of hydrophilic colloidal substances and has a high water content. Therefore, it is difficult to

  dehydrate them directly in their initial state. We add

  So you have a coagulant in this sludge, so as to coagulate the solids. The sludge is then dewatered to form a thick mud, hereinafter referred to as "filter cake". This cake can be rejected in the state or after its incineration. An inorganic coagulant, such as

  ferric chloride or slaked lime, is most frequently

  used as a coagulant and vacuum filtration

  is generally adopted for this mechanical dehydration.

  However, since the inorganic coagulant is added in relatively large amounts to solids in the

  mud, the amount of filter cake to be evacuated

  mented. In case the cake is burned, it is formed

  a large amount of ash and the fuel efficiency

  the filter cake is reduced by the incorporation

  coagulant. In addition, during the dehydration phase,

  ferric chloride or calcium carbonate is deposited on the filter web of dehydration, which

  leads to a decrease in filtration efficiency.

  A process is also known in which an organic polymer, hereinafter referred to as "coagulant polymer", is used as coagulant in order to coagulate the

  mud and form a flock which is then dehydrated

  caniquement. This process is advantageous in relation to this

  he uses an inorganic filler, because the amount of filter cake and the amount of ash left after burning the cake are decreased. However, the water retention rate of the flock formed by coagulation is high and, since the water is not easily separated from the floc, it is easily broken. Therefore, vacuum filtration or pressure filtration can not be used to dehydrate this floc.

  which requires dehydration by centrifugal

  fugation. However, dehydration by centrifugation does not significantly reduce the water content of the cake. In

  Moreover, this process using an organic polymer

  that coagulation has a disadvantage in that the

cost of treatment is increased.

  It is sought to improve the filterability of

  sludge and in particular organic sludge

  hydration is very difficult, for example sludge

  urban wastewater. It has been found that when a

  polypropylene, vinylon, polyester or nylon is

  in a mud and then add a poly-

  coagulating mother, the resistance of a floc obtained by coagulation

  gulation is increased and the compressibility of the floc

  is improved. As a result, filterability or

  the dewatering capacity of the sludge is greatly improved.

  SOE. It has also been found that good results are

  likewise obtained when a fiber is dispersed in a

  aqueous solution of a coagulant polymer and that this dispersion is added to a sludge. On the other hand, it has been found that when an inorganic coagulant is added to a sludge and the coagulated sludge is mechanically dehydrated, if a fiber is incorporated in combination with the coagulant, the

  filterability is significantly improved and the separation

  The cake of the filter cloth is obtained more

  and with the usual process. The pre-

  This invention is based on the ideas above.

  The present invention relates to a sludge treatment process that avoids the disadvantages of known methods. It significantly improves sludge filterability, even when using common coagulants, and facilitates post-treatment

filter cakes.

  More particularly, the present invention

  is aimed at a sludge treatment process that includes

  corporation and mixing a fiber and a coagulant in a mud in order to coagulate the solids of the

  mud, and dehydration of the coagulated mud.

  In the present description and the claims

  the term "sludge" means urban wastewater sludge, eg fresh sludge, digested sludge and mixtures of such sludge formed in sewage treatment plants,

  drainage, sludge formed in the

  ration and water supply, sludge deposited and

  at the bottom of rivers, lakes, ports and seas, and

  industrial wastewater sludge.

  According to the present invention, a

  fiber in a sludge to be treated, in association with a co-

  gulant. As a fiber usable in the present invention,

  for example, non-organic fibers, such as

  asbestos fibers, glass fibers and mineral wool fibers, natural or manufactured organic fibers, such as cotton fibers, flax, hemp, horsehair, wool, paper,

  pulp, rayon and cellulose acetate, syn-

  theories, such as polyester fibers, vinylon, poly-

  amide, aromatic polyamide, acrylic fibers, polypropylene fibers, polyvinyl chloride and polyvinylidene, carbon fibers and metal fibers. The length of the fiber which is used in the present invention is generally from 1 to about 50 mm, and preferably from 2 to

About 30 mm.

  The shape of the fiber is not imperative in

  the present invention, but it is generally preferred to

  obtained by cutting off a monofilament of one

  usually less than about 100 deniers, or

  a fiber formed by grouping a plurality of filaments

  treating said bundled filaments with a binder and cutting off the bonded filaments, or a fiber formed by bundling a plurality of filaments into a yarn and cutting the resulting yarn. On the other hand, a woven fabric, a nonwoven fabric, or a net may be

  used after being properly cut or

the.

  These fibers may be new fibers

  prepared fibers, regenerated fibers, waste

  bres or waste fibers. For example, we can use

  waste fibers obtained by finely cutting used clothing or textiles, fibers obtained

  threshing and disentangling of cut pieces by means of a bat-

  tor, and fiber waste from pneumatic cables

  obtained during the spraying of rubber tires

  rubber for automobiles to form a rubber

powder or recovery.

  Fibers whose surface is treated with a surfactant or dispersant, or fibers which have not been used, can be used in the present invention.

  not subjected to such a surface treatment.

  The addition of a fiber to a sludge facilitates the formation of uetloc by a coagulant and, at the same time, the

  resistance of the formed floc is increased and compressibility

  The floc quality is improved. In addition, the addition of the fiber to a slurry accelerates the separation of the water, which allows rapid dewatering, and the water content in a filter cake is reduced, which facilitates the

cake handling.

  Particularly good results are obtained when the fiber used is an organic fiber. More particularly, the combustibility of a filter cake

  in the combustion operation is increased by the pre-

  presence of the organic fiber. The amount of ashes

  combustion is reduced and we obtain a

  quality when the filter cake is transformed

fertilizer.

  The amount of fiber used varies according to the type and characteristics of the sludge to be treated, the

  type of fiber and coagulant used and the conditions

  treatment, but fiber is generally used

  about 0.05 to 150% by weight, and preferably about 0.1 to 100% by weight, based on

  solids contained in the mud. When the quantity

  fiber content is less than 0.05% by weight

  to solids in the mud, you can not get

  a significant increase in the improvement effect of

  filterability by increasing the amount of

  used but the viscosity of the sludge is increased and tangles of the fiber occur, making

  the following difficult operations. On the other hand,

  corporation of too much fiber is not economically advantageous. When the

  The sludge is treated in large quantities by

  if the fiber is incorporated in significant quantities

  aunt, the mechanical dehydration operation becomes difficult. Therefore, it is advantageous to incorporate the fiber up to a content of 20% by weight relative to

  to solids in the mud. We can adopt

  processes-to add the fiber to a sludge. For example

  a process in which the fiber is directly added to a slurry and mixed with the slurry, a process in which the fiber is incorporated and dispersed in an aqueous solution of a coagulating polymer, the dispersion being incorporated and mixed into sludge, and a process in which the fiber is incorporated and

  dispersed in water, a surfactant or dispersant

  being added to the demand and the dispersion being

incorporated into a mud.

  In each process, it is advantageous that the

  fiber is dispersed in a slurry in the same homogeneous

  gene as possible. The point of addition of the fiber to a slurry is not imperative, but in general the fiber is added to a sludge before the incorporation of a coagulant, or the fiber is added to the sludge at the same time as the coagulant. When the fiber is added to the mud after

  incorporation of the coagulant into the mud, a sufficient effect

  can hardly be obtained by the addition of the fiber. However, when two or more coagulants are added to a sludge, these coagulants are added to the sludge twice and coagulation begins first with the addition of the last coagulant, the fiber can be added at an intermediate point. after addition

  the first coagulant and before adding the last coagulum

  lant. Known coagulants can be used in the practice of the present invention. By and large, the coagulants are divided into inorganic coagulants

  and organic coagulants. As non-orgard coagulants.

  Examples include aluminum sulphate, basic aluminum chloride, ferrous sulphate, ferric sulphate, chlorine products rFeCI3 + Fe2 (WI17, ferric chloride, alum, quicklime and lime). off.

  Coagulating polymers include

  natural products and synthetic products and they are

  classified as anionic coagulants, cationic coagulants

  nonionic products with surface action and

  Amphoteric gulants, according to the ionic characteristics.

  As the anionic coagulant polymer, mention may be made of products such as polyacrylic acid salts,

  copolymer of acrylic acid-maleic acid, copolymer

  acrylamide-sodium acrylate resins, acrylamide copolymers,

  sodium lamide-vinylsulfonate, partial polyacrylamide

  hydrolysed, sodium salt of carboxymethyl cellulose

  lose and sodium alginate. Examples of cationic coagulant polymers that may be mentioned are products such

  polydialkylaminoalkyl methacrylates, polyamino-

  methylacrylamide, polyvinylpyridium salts, polydiacrylammonium salts, polyvinylimidazoline, polyamines, polyethyleneimines, cationic derivatives and cationic copolymers of polyacrylamide, hydrochloride resins

  of water-soluble aniline, polycondensates of hexamethyl

  thylenediamine-epichlorohydrin, chitosan and starch

  tionique. As a nonionic coagulating polymer, it is possible

  for example, to use products such as polyacrylate

  mide, polyvinyl alcohol, polyethylene oxide,

  lyvinyl pyrrolidone, urea-soluble resins in water,

  starch, prulan and gum As an ampholytic coagulant polymer

For example, gelatin can be mentioned.

  When treating organic sludge or

  sludge containing large quantities of colloidal

  dales or fine particles, the coagulant polymers

  These other coagulants can be used alone, or

  as a mixture of two or more of them.

  To promote the effects of coagulation and dehydration of the cagulant, it is possible to use pH correction products, coagulation adjuvants,

  surfactants and soluble salts in water.

  As a pH correction reagent, it is possible to use

  sulfuric acid, hydrochloric acid,

  nitric acid, sulfamic acid, carbon dioxide, acetic acid, sodium hydroxide, carbonate of

  sodium, quicklime and slaked lime. As adjut

  before coagulation, products such as

  bentonite, kaolin, acidic clay, zeolite, earth dia-

  tomatoes, activated clay and activated charcoal. Agents tend

  The active agents include cationic, anionic and

  nonionic and amphoteric Any agent

  surfactant can be used in the present invention.

  tion, but surfactants are generally preferred.

  cationic assets. For example, preference is

  this products such as monoamines, diamines, triamines,

  and aliphatic and aromatic amidoamines having a

  eg high alkyl, polyaminoethyl imidazolines, higher hydroxyalkyl alkylene diamines, amino-resins, their

  adducts with ethylene oxide, ammonium salts

  quaternary monium and acid soluble in water of

  these amines and adducts of ethylene oxide

  lene. The combined use of a surfactant

  and coagulant is very effective for the treatment of

  organic sludge and sludge containing

  colloidal stanzas. In addition, since the amount of

  can be reduced by the combined use of an agent

  surfactant with the coagulant, good results are obtained.

  in the dehydration of a large quantity of sludge.

  As the water-soluble salt, there may be mentioned, for example, the salts of K, Na, Li, Sr, NH 4, Ca, Mg, Zn, Fe, Ba and Al.

  hydrochloric acid, nitric acid, sulfuric acid

  liquid, sulphamic acid and acetic acid.

  In the present invention, the coagulant and the coagulation adjuvant can be introduced by the usual methods and the amounts used for these purposes.

  agents are equal to or less than the general quantities

  used in the treatment of sludge. For example

  when an urban waste water sludge is treated

  With ferric chloride and slaked lime, ferric chloride is usually added in an amount of from about 3 to about 12 percent by weight based on the solids in the slurry, and the slaked lime is added in an amount of about 10 to about 10 percent by weight. compared to solids in the mud. When using a coagulant polymer for

  treatment of an urban waste water sludge, this

  The coagulant is added at a rate of 0.01 to 5%

  preferably about 0.05 to 3% by weight,

  weight relative to the solids in the sludge.

  These coagulants can be used alone, or in the form of a mixture of two or more of

  them, and the incorporation of these coagulants can be effected

  made by known methods. We can use

  coagulating polymers with different ionic characteristics

  in association, or use a polymer and a

  non-organic coagulant in combination.

  As previously indicated, the coagulant is added to a slurry after the fiber has been incorporated and mixed into the slurry, or the coagulant is added to the slurry along with the fiber. When the coagulant is thus added to a sludge, the solids in the slurry are immediately coagulated to form a floc, while causing the solid-liquid separation. Since the fiber promotes the dehydration of the floc, it is possible to obtain

  a good effect of water separation or dehydration effect

  in this floc, even in the case of dehydration by gravity. Moreover, if a slight pressure is applied to this filtration residue, the water in the floc can be

  easily eliminated. As a result, when the mud is

  when dried and dehydrated by a machine such as a belt filter, a decanter or a belt / belt type dewatering apparatus, the dehydration of the interior of the cake is favored by the fiber while the cake is reinforced by the fiber, the compressibility of the cake

  being greatly improved. As a result, dehydration

  it is easy to erect and erase easily and to obtain a filter cake with a low water content. In addition, clogging

  filtering cloth is greatly reduced and the evacuation

  The cake of the filter cloth is remarkably facilitated. The features and effects of the following sludge treatment process are described below.

the present invention.

  (1) When an inorganic coagulant is used as a coagulant for a sludge, if the fiber is used in combination with the following non-organic coagulant

  the method of the present invention, the speed of

  Sludge hydration is substantially increased and filterability is greatly improved. In addition, the

turbidity of the filtrate is reduced.

  (2) When using a polymer as a coagulant for a sludge, even if the treatment is very difficult with a small amount of the polymer used alone, the

  The treatment can be carried out advantageously if the

  is used in combination with the polymer,

  according to the process according to the invention.

  (3) When using a single polymer, the types of sludge that can be treated are limited but,

  if the fiber is used in combination with the poly-

  coagulating mother, this limitation disappears and one can obtain a high treatment effect, stably,

regardless of the type of mud.

  (4) Even in the case of organic sludge,

  that a noticeable treatment effect

  By using a highly cationic polymer according to the usual method, a

  high treatment with the process of the present invention.

  even when using a moderately or moderately

weakly cationic.

  (5) Where the process according to this

  In the invention, the resistance of the formed floc is increased and the filterability is remarkably improved. Since the filterability is high and the water content of the filter cake is low, the incineration cost is reduced for the incineration phase of the cake. When the fiber used is an organic fiber, an effect of facility of incineration can be obtained, according to the quantity

of organic fiber incorporated.

  (6) The process according to the invention provides a satisfactory treatment effect even at low temperatures and the treatment efficiency at low temperatures is substantially improved compared to the low temperature treatment yield which can be achieved by

known methods.

  (7) The method according to the present invention can be implemented by means of existing equipment and the processing capacity of the equipment is increased

  by adopting the process according to the invention.

  (8) A non-coagulant can be used effectively

  organic material or a coagulating polymer, in the process

  the invention. On the other hand, we can obtain

  satisfactory results, even if a polymer is used

anionic or nonionic.

  The method according to the invention, described above, provides various effects and excellent characteristics,

  as indicated above, and this method is particularly suitable

* for the treatment of sewage sludge. In

  furthermore, the method according to the present invention

  advantageously to the treatment of discharges of raw materials, feedwater treatment sludge, sludge deposited at the bottom of rivers, lakes, ports and seas and sludge industrial effluents. The following process

  the present invention gives very good results when

  sludge is mechanically dehydrated but also

  when applied to treatments in the-

  which one does not perform mechanical dehydration, because

  gravity dehydration is remarkably improved

  SOE. The present invention is hereinafter described in detail with reference to non-limiting examples. These

  examples illustrate the treatment of sludge

  urban dunes, which are organic sludges whose

  Dehydration is the most difficult.

EXAMPLE 1

  100 g of fresh mixed sludge of wastewater (solid content = 3.5% in

  weight, fire loss of solids = 54% by weight), a

  Polypropylene (manufactured and sold under the name

  "-P-chopa by Chisso Corporation), in indi-

  Table 1 (see page 20). We stir the

  lange for about a minute. Then we add to the mix

  an aqueous solution of ferric chloride (300 Baumé) and slaked lime, in the amounts indicated in

  Table 1. The filterability and the trans-

  filtrate mission by testing Nutsche and we get

  the results shown in Table 1.

  By way of comparison, ferric chloride and slaked lime are added to the same mud as that of Example 1, but without adding fiber. The mixture is treated and controlled as indicated above. The results obtained are shown in Table 11

  The test method adopted is described below. It is

  Nutsche test git, in accordance with the release test methods, published by Japan Sewage Works Association &

  A coagulant is added to 100 g of residual water sludge.

  res, to which a fiber is added or not. The mixture is stirred and then loaded into a filter bottle and

  subjected to vacuum filtration, atmospheric pressure and

  at 100 mmHg. We determine (1) the time in sec-

  necessary for the formation of 50 ml of filtrate and (2) the quantity in ml of the filtrate obtained in 30 seconds

  from the beginning of the filtration. In addition, (3)

  the transmission of the filtrate when the sludge is fil-

  until the water disappears from the surface of the mud. The transmission is expressed in calculated relative value, based on the assumption that the transmission of

the city water is 1CKP.

EXAMPLE 2

  100 g of fresh mixed sludge of wastewater (solids content = 3% by weight, solids loss of solids = 54% by weight) are added to the polypropylene fiber P-Chop in the amounts indicated in Table 2 (see page 21). The mixture is stirred

  about a minute. Then an aqueous solution is added

  0.2% by weight of a cationic coagulant polymer

  manufactured and sold under the name of Accofloc C485 by Mitsui-

  Cyanamide Ltd, in the amounts shown in Table 2.

  The mixture is stirred for about one minute. A floc is formed immediately. Then, the filtration and solid-liquid separation test (gravity filtration and compression filtration) is carried out and the amount of separated water and the water content of the filter cake are measured after the gravitational filtration. The results

  obtained are shown in Table 2.

  By way of comparison, only the coagulant is added, in the same way, to the same mud as in Example 2,

  without addition of the fiber. The mixture is processed and es-

  tried in the same way as above. The results obtained

  are shown in Table 2.

  The filtration test method adopted is described below.

  after. This is the gravity filtration test: A predetermined amount of a coagulant is added to a slurry, to which a fiber has or has not been added. The mixture is stirred for about one minute to form a floc. The solid-liquid mixture is poured onto a polypropylene filter cloth placed on a 200 ml beaker and allowed to stand for one minute. The amount of water in ml that flows into the beaker in one minute is measured and this quantity is considered the

amount of water separated.

  The compression filtration test is now described: After the gravitational filtration test described above,

  a steel column with a diameter of 7.5 cm

  viron, with a height of approximately 8.6 cm and a weight of

  3 kg, so as to exert a fixed charge for 30 seconds.

  condes on the mud, on the filter cloth. The amount of water in milliliters that flows into the beaker during

  this period is measured. The sum (in ml) of the quantity

  water content measured and the amount of water separated

  measured during the gravity filtration test is considered to be the quantity (in ml) of water separated

  the compression filtration test.

  The water content of the filter cake is now defined.

  After compression filtration: When the compression filtration was carried out for 30 seconds, the steel column is immediately removed and the water content of the filter cake is measured.

in weighted percentage.

EXAMPLE 3

  To 100 g of the same mixed

  in example 2, the P-Chop fiber in amounts indicated in Table 3 (see page

  22). The mixture is stirred for about one minute. In-

  Then, an aqueous solution containing 0.2% by weight of a cationic coagulant polymer manufactured and sold under the name "Accofloc C451" by Mitsui-Cyanamide Ltd is added to the mixture in the amounts indicated in Table 3. The mixture is stirred at room temperature. mix for about a minute and form flake immediately. The filtration and solid-liquid separation test (gravity filtration and compression filtration) is carried out in the same way as in

  example 2. Measure the amount of separated water and the

  in water from the filter cake after compression filtration. The results obtained are reported in the

table 3.

  By way of comparison, only the coagulant is added to the

  same slurry as in Example 3, without addition of P-Chop.

  The mixture is treated and tested in the same way as in Example 3. The results obtained are indicated in FIG.

table 3.

EXAMPLE 4

  Dissolve in 100 parts by weight of water,

  0.2 parts by weight of Accofloc C485 and the final

  P-Chop to the solution, in the amount indicated in

  Table 4 (see page 23), to form a solution

  of a coagulant polymer with incorporated fiber. Then 7 grams of the coagulant solution and

  obtained at 100 g of the same sludge of residual water

  as in Example 2. The mixture is stirred for a

  minute, to form a floc. The filter test

  solid-liquid separation and separation (gravi-

  silage and compression filtration) is performed and the amount of water separated and the water content of the cake

  after compression filtration are measured

  Rees. The results obtained are reported in the table.

Bleau 4.

  By way of comparison, a solution of the polymer but without addition of fiber is added in the same way to the same slurry as in Example 4. The mixture is treated

  and tried in the same way as in Example 4. The

  The results obtained are shown in Table 4.

EXAMPLE 5

  0.2 parts by weight of Accofloc C451 are dissolved

  in 100 parts by weight of water. The P-Chop fiber is added

  to the solution, in the quantity indicated in Table 5

  (see page 24), to form an aqueous solution of a

  lymere with incorporation of fiber. 7 grams of the coagulant solution thus obtained are then added to 100 g of the same sludge as in Example 2. The mixture is stirred for about one minute to form a mixture.

  floc. The filtration and solid separation test

  liquid (gravitational filtration and compression filtration) is carried out and the amount of water separated and the water content of the filter cake is measured naked Ob

  compression filtration. The results / are reported

in Table 5.

  By way of comparison, one adds in the same way a

  the aqueous solution of the polymer, without fiber, at the same temperature as in Example 5. The mixture is treated and tested in the same manner as in Example 5. The results

  obtained are shown in Table 5.

EXAMPLE 6

  0.1 part by weight of Accofloc C485 is dissolved in 100 parts by weight of water. We add to the solution

  P-Chop fiber with a fiber length of 5 mm, in

  indicated in Table 6 (see page 25) to

  an aqueous solution of coagulating polymer with

  fiber corporation. Then the solution of

  coagulant thus obtained, in the amount indicated in

  Figure 6, at 100 g / digested digestions (solids content = 3% by weight, solids loss to solids = 60% by weight). It is stirred for about a minute,

  to form a flock. The filtration and separation test

  solid-liquid filtration (gravity filtration and compression filtration) is carried out and the quantity

  water content and the water content of the filter cake a-

  near compression filtration.

  The results obtained are shown in Table 6.

  By way of comparison, one adds in the same way a

  Acfofoc C-485 aqueous solution, without fiber, at the same time

  mud than in Example 6. The mixture is processed and

  tried in the same way as in example 6. The results

  obtained are shown in Table 6.

EXAMPLE 7

  0.2 parts by weight of Accofloc are dissolved

  C485 and 0.1 parts by weight of a quaternary ammonium salt

  of a tallow amine ethylene oxide adduct, as a cationic surfactant, in 100 parts by weight of water. The P-Chop fiber is incorporated and dispersed in the solution, in the amount indicated in Table 7 (see page 26), to form a solution

  aqueous fiber coagulant incorporated. We add

  7 g of the coagulant solution thus obtained are then treated with a fresh sludge of waste water (solid content = 2.8% by weight, solid loss on ignition = 65%

  in weight). The mixture is stirred for about one minute.

  ron. The filtration test (gravity filtration and filtration

  compression treatment) is carried out and the amount of separated water and the water content of the filter cake is measured after the compression filtration. The results

  obtained are shown in Table 7.

EXAMPLE 8

  To 100 g of the same fresh mud is added

  0.1 g or 0.3 g of vinylon A fiber (denier size, length 5 mm) or vinylon B fiber (denier size, length 10 mm) was added to that in Example 1.

  mix 7 g of a 0.2% aqueous solution of Accofloc C485.

  The mixture is stirred for about 1 minute to form

  a flock. The filtration and solid separation test

  liquid (gravitational filtration and compres-

  is performed and the amount of separated water

  and the water content of the filter cake after filtering

  compression. The results obtained are as good as those obtained in Example 2e

EXAMPLE 9

  0.2 parts by weight of Accofloc C451 are dissolved in 100 parts by weight of water. One part by weight of a polyester fiber (denier size, length 5 mm) is incorporated and dispersed in the solution, to form

  an aqueous solution of a coagulating polymer with incor-

  then add 7 g of the solution

  of coagulant thus obtained to 100 g of the same sludge

  The mixture is stirred as in Example 2 and the mixture is stirred for about one minute to form a floc. The test

  filtration and solid-liquid separation (filter

  gravity and compression filtration) is

  killed and we measure the amount of separated water and the content

  in filter cake water after filtration by

  pressure. We get very good results.

EXAMPLE 10

  The same cationic surfactant product is added

  that (not added in some tests) than in Example 7 and PChop fiber (size 2 denier, length 5 mm), in amounts indicated in Table 8 (see FIG.

  page 27) to the same mixed fresh mud as in the example

  The mixture is stirred for about one minute. A 0.2% by weight aqueous solution of Accofloc C485 is then added to the mixture, in an amount indicated in FIG.

  Table 8. The mixture is stirred for 30 seconds in

  viron and a floc forms immediately. Subsequently,

  the mixture to the filtration and dewatering test

  by means of a pressure band type filter.

  The results obtained are shown in Table 8.

  By way of comparison, the filtration and

  Hydration is carried out in the same way as above but without addition of fiber. The results obtained are

shown in Table 8.

EXAMPLE 11

  A solution of coagulant is prepared by

  solution and dispersion in Accofloc C485 water, that is to say the same cationic surfactant product as in Example 7, and PChop fiber (2 denier size, length 5 mm), in amounts indicated in table

  9 (see page 29). The coagulant solution is added

  in the amounts indicated in Table 9, to the same fresh sludge as in Example 7. The mixture is stirred for about one minute to form a floc. The filtration and dewatering test is carried out by means of a press belt type filter. The results obtained are shown in Table 9.

  By way of comparison, the filtration and

  shydration is carried out in the manner previously described

  except that the fiber is not incorporated in the coagulant solution. The results obtained are

reported in Table 9.

  It is understood that modifications of detail may be made in the form and implementation of the method according to the invention, without departing from the scope thereof.

TABLE 1

  Test Quantities added, relative to solid N in sludge. Aqueous solution P-Chop iron-extinguishing chloride lime,

  (Baumé) (% e Quantity Lon-

  % by weight weight) added (% in (mm) weight) fiber Nutsche Test Time (seconds) required

to the

  ml of filtrate Quantity (ml)

of fil-

Trat trained in

secondary

of the

trans-

  Comparison of the filtrate Present invention 1 1 Comparison 2.9 14.3 28.6 2.9 14.3 28.6 2.9 14.3 28.6 2.9 14.3 28.6 2.5 2.5 2.5, 0, 0, 0 2.5 2.5 2.5, 0, 0, 0 22.0 14.0 12.0 22.0 19.0, 0

- 57.0

- 408

  oh, 6 96.7 96.0 96.3 97.8 94.4 92.5 94.3 93.4 91.3 88.2 89.7 58.1 72.0 72, 3, 0 67.8 71.0 18.3 29.1 28.8, 9 21.2 36.3 33.9 11.0 88.4, 6 Bones 0% Co \ 0

I '' -

"; ' 1

TABLE 2

Quantity added (g)

of solu-

  0.2% Accofloc C485 Quantity (ml)

of water

  prepared in gravity filtration Quantity (ml)

of water

Filtered in filtration

by com

  pressure Water content (% by weight) of the filter cake

after

tration

by com

  pressure Present invention Comparison

7,100

  Test NO Weight (g) of slurry P-Chop Fiber length (mm) Amount added (a) 2.5 2.5, 0, 0, 0 0.1 0.5 1.0 0.1 0.5 1 , 0 7.0 7.0 7.0 7.0 7.0 61.0 62.0 66.0 61.5 62.5, 0, 0, 0 82.0 88.0 83.0 83.5, 0 74.5 7.0 88.5, 7 78.9 87.1, 1 81.8, 8 Co \ 0 Ili Test Weight No (g) sludge P-Chop Length Quantity of fiber added ( mm) (g)

TABLE 3

  Quantity Quantity -.Quantity Additive content (ml) (ml) water (g) of water with water content (% by weight) of solution in filter filtration

  0.2% by gravity

of Accofloc pressure tration

C451 by

  Comparison 2.5 2,5, 0, 0 0.5 1 0 0.5 1 0 7.0 7.0 7.0 7.0 61.0 62.0 61.0 62.5 87 , 5, 5 88.0 89.0 82.1 77.1 81.6 77, 8 7.0 59.5 73.0 91.2 1-J

TABLE 4

  Test Composition of Accofloc water coagulant solution (C485 parts in weight) (parts ___, by weight) P-Chop Lon- Quantity added (fiber parts in (mm) weight) Quantity (g)

of solu-

tion of

coagulated

  lant added to 10 g of sludge Quantity (ml)

of water

adorned in

filtration

tion

gravitation

Quantity (ml)

of water

adorned in

filtration

by

compressive

  water content (% by weight) of the filter cake

after

tration

by com

  pressure Present Invention Comparison NO 0.2 0.2 0.2 0.2 2.5 22 95 2.5, 0, 0 1.0 1.0 3.0 7.0 7.0 7.0 7.0 66.0 68.0 67.0 69.0 0.2 84.0 87.0, 5 86, 0 86.7 83.9, 7 84.7 to 7.0, 0 74.5, 8 0% > 0% Co co O0J

TABLE 5

  Test Composition of the coagulant NO solution Water (parts by weight) Accofloc C451 (parts by weight) P-Chop Fiber length (mm) Amount added (parts by weight) Quantity (g)

of solu-

tion of

coagulated

  lant added to 100g of sludge Quantity (ml)

of water

adorned in

filtration

* tion

gravitation

Quantity (ml)

of water

adorned in

filtration

by

compressive

  Water content (% by weight) of the filter cake

after

tration

by com

  pressure Present Invention Comparison 0.2 0.2 0.2 0.2, 0, 0 0.5 1 0 0.5 1.0 7.0 7.0 7.0 66.0 66.5 67 , 0, 0 79.0 82.0 81.0 84.5 0.2 89.2 87.7 88.3 86.4 7.0 59.5 73.0 91.2 os 0% CD Co \ 0 this

TABLE 6

  Composition of the coagulant Water (parts by weight) ACcofloc C485 (parts by weight) P-Chop solution (fiber length mm, (parts by weight) Quantity (g)

of solu-

tion of

coagulated

  lant added to 100 g of sludge Quantity Quantity (ml) (ml)

of sewage water

decked out in

filtra-filtra-

tion by

gravity

  water content (% by weight) of the filter cake

after

tration

by com

  pressure Presents ihvention Comparison

7,100

9,100

  Test No 0.1 0.1 0.1 0.1 0.1 0.1 0.5 0.5 0.5 1 0 1 0 1.0, 0 12.0 14.0, 0 12.0 14 , 72.0, 0.74, 0.70, 79.0, 91.8, 89.0, 91.0, 96.5, 87p3, 83.8, 5, 482.5, 0. , 1 0.1 0.1, 0 12.0 14.0 57.5, 66.0 69.5 73.0 79.0 92.6 92.3 91.4 os' Oa ce -O

TABLE 7

  Composition of the coaaulant solution Water (parts by weight) Accofloc C485 (parts by weight) Product

surfactants

  active (parts by weight) P-Chop Fiber length tmmY Amount added (parts by weight) Quantity (g)

of solu-

tion of

coagulated

  lant added to 100g of sludge Quantity (ml)

of water

adorned in

filtration

tion

gravitation

Quantity (ml)

of water

adorned in

filtration

by

compressive

  Water content (% by weight) of the filter cake

after

tration

by com

pressure Present invention

0.1 2.5 1.0

0.1 2.5 3.0

0.1 5.0 1.0

0.1 5.0 3.0

  Test No. 0.2 0.2 0.2 0.2 7.0 7.0 7.0 7.0 67.0 69.0 67.5 69.0 86.5 87.5 87.0 89.0 84.9 83.5 84.5 82.0 ru o oe% 0

TABLE 8

  Test NO quantity of sludge (parts by weight) Quantity of product

surfactants

  active (parts by weight) Quantity Quantity

of P-Chop of solu-

(parts to 0.2%)

weight)

  flock C485 (parts by weight) Leakage of the cloth

filtran-

  Exit state of the filter cake Water content (% by weight) of the filter cake Present invention

2,100

4,100

  o 0.05 0.05 0.05 Comparison o bad bad o 0.10 0.05 0.10 0.20 good good good good -j good good good good 0o rO 0% 1-4 TABLE 8 (Continued) Note s Leaking filter cloth:

  The leakage of mud flocs through the side face

  in the pressing zone and the escape of mud flocs by the woven texture of the filter cloth are examined and evaluated as follows: good: no acceptable leakage: slight leakage bad: leak observed over the entire surface. * Output state of the filter cake:

  The state of exit of the cake of the wire cloth

  trante is examined and evaluated as follows t good: the cake comes off regularly without adhering to the filter cloth and

without clogging this canvas.

  acceptable: the cake separates, with a

  slight adhesion to the filter cloth.

  my go: the cake does not separate regularly

  first, he strongly adheres to the

  filter cloth and there is a cer-

some clogging of this cloth.

  ** Water content of the filter cake: The water content of the cake is measured by

the JIS A-1203 method.

TABLE 9

  Test Composition of the coaaulant solution Water Accofloc (parts C485 by weight) (parts by weight) Product

surfactants

  active (parts by weight) P-Chop (parts by weight) Quantity Leakage of (parts the cloth

by weight)

  solution of coagulant added to 100 parts by weight of sludge Outlet state of the filter cake Water content (% by weight) of the filter cake Present Invention

2,100

  Comparison 7 bad bad NO 0.2 0.2 0.2 0.05 0.05 0.05 0.5 1.0 2.0 good good good to 0.2 good good good ro oe Co% O "to

Claims (6)

  1. Sludge treatment process, characterized in that it consists of incorporating and mixing a fiber and a coagulant in a sludge to coagulate the solids contained in the sludge, and to dehydrate the coagulated sludge. 2. Method according to claim 1, characterized   in that the fiber is at least one of the products belonging to   in the group of inorganic fibers, natural organic fibers, manufactured fibers,   synthetic fibers, carbon fibers and metal burrs.   3. Method according to claim 1, characterized in that the fiber is incorporated in a proportion of 0.05 to% by weight relative to the solids contained in the mud.   4. Process according to claim 1, characterized   in this. that the coagulant is an inorganic coagulant.   5. Process according to claim 1, characterized   in that the coagulant is a polymer.   6. Process according to claim 1, characterized   in that a surfactant product is used in combination with its with the coagulant.